In a sweet display of sibling affection that went otherwise unnoticed, Princess Charlotte appeared to wave her flag in the direction of her older brother's face - with a twinkle in her eye that suggested she was hoping to annoy her big brother.
With a look of focus, the seven-year-old appeared in high spirits as she gently waved her Union Jack flag towards Prince George.
WATCH: Prince William and Prince George duet to Sweet Caroline at Jubilee concert
What's even funnier is Prince George's apparent refusal to get drawn into the funny moment! Refusing to react to Charlotte, the eight-year-old appeared nonplussed and continued to enjoy the joyous concert. With his eyebrows slightly raised, the young royal was not impressed by his sister's antics.
The pair attended the BBC's Party at the Palace alongside their parents the Duke and Duchess of Cambridge. The family enjoyed performances from the likes of Diana Ross, Alicia Keys, Nile Rodgers, Andrea Bocelli and Duran Duran.
The duo appeared to thoroughly enjoy the Jubilee concert
Other royals in attendance included Mike and Zara Tindall, who sat behind the Cambridges, Prince Charles and the Duchess of Cornwall and Prince Edward and the Countess of Wessex, along with their children Lady Louise Windsor and James Viscount Severn.
This isn't the first time the duo have delighted fans with their escapades. In a candid photo taken during their visit to Cardiff Castle, Princess Charlotte laughed uncontrollably alongside her older brother.
The sweet snap was taken as Charlotte took over from conductor John Quirk and started conducting an orchestra playing, We Don’t Talk About Bruno, from Disney's Encanto.
Charlotte relished the moment
Clearly enjoying the moment, Charlotte let loose a toothy grin whilst George looked on supportively with a shy smile.
To round off the jam-packed weekend, The Jubilee Pageant will take to the streets of London on Sunday in a spectacular £15 million procession. Stars including Idris Elba and Sir Cliff Richard are set to appear in open-top buses in a through-the-ages tribute to the culture and music of the Queen's 70-year reign.
It is hoped the monarch will make a final appearance on the Palace balcony to witness Ed Sheeran singing the national anthem with a choir made up of nearly 200 celebrities.
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